Steam generator with forced passage of the operating medium



April 12, `193.8. MQEULE 2,113,833

STEAM GENERATOR WITH FORCED PASSAGE OF THE @P ERATING MEDIUM Filed Dec.. so, 195e 2 sheets-sheet 1 wn mmmV m L HM' (13M) April 12, 1938.A M. EULE 2,113,833

` STEAM GENERATOR WITH FORCED PASSAGE OF THE OPERATING MEDIUM Filed Deo. 50, 1936 '2 Sheets-Sheet 2 invention in yUNITED-s'r-ATES PATENT OFFICE 2,113,833 GENERATOR wrrn FORCED ms- STEAM SAGE O Martin Eule, Berlinto Siemens-Schucker Berlin-Siemensstadt, Germany, a corporation of Germany Applicatio In Germ 3 Claims.

My invention relates to improvements in steam generators with forced passage of medium.

the operating In generators of the above character it is well known in the art to an automatic control. in pulses occurring inA operation are which th provide the generator with e control imderived from the changes in temperature of the operating mcdium contained in the preheater or superheater. By the impulses derived from these heating surface portions it is, however, not possible to attain a satisfactory control, since depending upon whether the preheater or the the impulses,

superheater be employed for 'deriving the impulses,

either arrive too soon or too late.

The

, obvious method of deriving at a suitable moment control impulses by pulse receiver into the evaporation placing the temperature imzone, located between the preheater and the superheater fails,

since in this heating'surface portion normally the pressure does not vary and the temperature remains constant independently fluctuations. There is, however, a

of the load simple meth'- od of deriving control impulses from the zone, in which the heating surface of evaporation lies in the path of the hot gases, which sists in providing heating surface proper inafter the main heating surface tube only traversed manner in which hot gases or arranged with method con-v besides the tubes forming the which I shall call herea measuring by liquid, heated by the same heat source as the main heating surface and parderiving impulses.

With to derive cerfrom any suitable point,

it is placed respect to the several main heating surface portions oi' the boiler.

However, the use of such a measuring tube is only of particular advantage if to utilize the considerable amount up by the measuring tube in such it is possible of heat taken a manner as not to require additional expensive devices.

This may be accomplished according to the a simple manner by liquid issuing operating medium traversing the surface of the boiler. To ensure stable conditions of flow.

supplying the from the measuring tube to the main heating in operation it is advisable to supply the liquid issuing from the measuring tube into the path ol the operating medium at a point at which only liquid flows.

Consequently, the

liquid is preferably supplied within. the range extending from the feed point of the boiler to the F THE OPERATING MEDIUM Spandau, Germany, assigner twerke Aktiengesellschaft,

n December 30, 1936, Serial No. 118,224

any December 31, 1935 point where the preheating of the operating medium ceases.

Another question which should also becarefully considered, if bythe use of a measuring tube particular advantages are to be obtained, concerns the suitable feeding of the measuring tube. In considering this question it is above all essential that the vquantities of liquid passing through the tubes forming the main heating surface as well as through the measuring tube should vary in the same proportion as the load of the boiler fluctuates. if always a true picture of the processes in the main heating surface oi' the generator should be given by the impulse derived from the measuring tube. Also in this case it is essential that no additional expensive de- A vices be required. This may be attained according to the invention by employing the feed pump of the boiler also for feeding the measuring tube. If the necessary conditions of flow in the measuring tube and in the main heating surface of the boiler to which the measuring tube is connected in parallel relation are not brought about by correspondingly proportioning the sectional areas of flow of the two parallel arranged parts, the desired conditions of ow may be also attained by inserting in the operating medium supply conduit of the boiler a throttle which is preferably capable of being regulated. The use of a throttle at this point permits, for instance, feeding of the measuring tube at a pressure higher than the generator inlet pressure, which will be in many cases of great importance, since there will always be a tendency to employ a comparatively narrow tube as a measuring tube so that the resistance to flow of the measuring tube may be, consequently, considerably greater than that of the main heating surface portion of the boiler to which the measuring tubeis connected in parallel relation. In this-case, the throttle lying in the operating medium' supply conduit of the boiler must be controlled to such an extent that the measuring tube, as isrequired in operation, contains always liquid throughout its length. If there is the quantities flowing through the boiler and the measuring tube is disturbed by the load fluctuations of the boiler this may be under certain circumstances avoided to advantage by inserting baille plates in the measuring tube and/orl in the operating medium supply conduit of the boiler.

A practical embodiment of my invention is represented in the accompanying drawings in which similar characters of reference indicate corresponding parts and in which Figs. 1 and 2 show the arrangement of the tubes in diagrammatic form, whereas Fig. 3 shows diagrammatically a steam generating plant embodying my invention. In the drawings I denotes the preheater, 2 the vaporizing heating surface, 3 the superheater. The operating medium is supplied to the boiler through the conduit l and the steam produced flows oif through the conduit 5. 6 is the measuring tube from which the temperature impulse is derived serving to control the boiler. As will be apparent the liquid issuing from the measuring tube 6 is in all cases supplied to the 'operating medium contained in the main heating surface of the boiler. In the arrangement shown in Fig. 1 the liquid is supplied to the main heating surfacev at a point located between .the preheater I and the evaporator heating surface 2, whereas in the arrangement according to Fig. 2 the liquid from the measuring tube is returned to the operating medium ahead of the preheater. As is indicated in Fig. 3 a throttle 1, which may have the form of a baille plate (not shown in detail) is inserted in the liquid supply conduit 4 between the feed pump and the boiler. Instead of a baiile plate any suitable equivalent, for instance a valve may be employed as shown in Fig. 2. The conduit l is tapped at a point ahead of throttle 1. From this point the measuring tube 6 receives its liquid. Under certain circumstances, it is preferable to insert a valve 8 into the measuring tube in order to influence the resistance to flow prevailing in the measuring tube 6 or, if desired, to dampen the oscillations of the liquid. The boiler is heated by a burner 9 which is fed with fuel through a conduit I0 by a pump Il. I2 is the driving motor for the pump II. The speed of the motor I2 may be regulated by the switch rheostat I3 whose switch Il may be rotated by an electric motor I5. 'I'his motor may be rotated in the one or the other direction depending upon which of the two relays I6 or I1 is operated. I8 and I9 indicate points at which the temperature is measured. In the arrangement shown in Fig. 3 thermo-elements are employed which may be inserted, for instance, in series in one branch of a Wheatstone bridge 20. In the diagonal conductor 2| of the bridge is inserted a measuring instrument 22 of a suitable type whose pointer connects the conductor 23 for energizing the rheostat coils I6 or I1 with the conductor 24 or 25 depending upon the manner in which the balance of the bridge is disturbed owing to the changes in temperature measured at the points I8 and/or I9. Accordingly either the relay I6 or the relay I1 is energized and operates the speed regulator for the motor I2 driving the pump II in the desired direction. 'I'he operating conditions are s o chosen that upon an increase in temperature at the points I8 and/or I9 the fuel supply from the pump II is reduced by lowering the pump speedand vice versa. The water is supplied by a pump 26 driven by a motor 21,

I claim as my invention;

1. In a forced flow tubular steam generator having a liquid operating medium supply ahd a fuel supply for heating its furnace, a measuring tbe traversed throughout only by a liquid medium similar to the generator medium, and disposed adjacent to and along at least a portion of the main tubular heating surface, so that its length in the furnace is exposed simultaneously and jointly with the main tubular heating surface to the temperatures of the furnace heat zones, and means for controlling the 'fuel supply in accordance with the temperature variations prevailing at the entrance of said measuring tube into and its exit from the furnace, and means for supplying the liquid issuing from said measuring tube into the medium flow path of said' generator at a point at which the operating medium is still in a liquid state.

2. Inaforcedow tubular steam generator having a liquid operating medium supply and a fuel supply for heating its furnace, a measuring tube traversed throughout only by a liquid medium similar to the generator medium, and connected for its medium supply to saidoperating medium supply, and disposed adjacent to and along at least a portion of the main tubular heating surface, so that its length in the furnace is exposed simultaneously and jointly with the main :tubular heating surface to the temperatures of the furnace heat zones, and means for controlling the fuel supply in accordance with the temperature variations prevailing at the entrance of said measuring tube into and its exit from the furnace, and means for supplying the liquid issuing from said measuring tube into the medium ow path of said generator at a point at which the operating medium is still in a liquid state.

3. In a forced flow tubular steam generator having a liquid operating medium supply and a fuel supply for heating its furnace, a measuring tube traversed throughout only by a liquid medium similar to the generator medium, and connected for its medium supply to said operating medium supply, and disposed adjacent to and along at least a portion of the main tubular heating surface, so that its length in the furnace is exposed simultaneously and jointly with the main tubular heating surface to the temperatures of the furnace heat zones, and means for controlling the fuel supply in accordance with the temperature variations prevailing at the entrance of said measuring tube into and its exit from the furnace, and means for supplying the liquid issuing from said measuring tube into the medium ow path of said generator at a point at which the operating medium is still in a liquid state, and

a ow resistance between said tubular generator and its operating medium supply, whereby said measuring tube is fed from said operating medium supply at a pressure higher than the pressure at which the medium nows into the generator.

'lio 

